In certain medical procedures, a generally flexible medical device or needle may be preferred over a generally rigid medical device or needle. For example, a generally flexible needle may be preferred during needle insertion and needle steering in the anatomy. In other medical procedures, however, a generally stiff or rigid needle may be preferred. Some medical procedures may require a surgeon to use a generally flexible needle and a generally rigid or stiff needle. For example, during a tissue sampling procedure, a surgeon may be required to insert and steer a generally flexible needle and catheter through the anatomy, remove the flexible needle form the catheter and the anatomy, and then insert a generally rigid needle into the catheter and the anatomy to perform the tissue sampling function at a site of interest. Accordingly, such a procedure may be cumbersome for the surgeon, time consuming, and may cause unnecessary trauma to the patient.
It may therefore be desirable to have a variable stiffness medical device. That is, it may be desirable to have a medical device that is generally flexible in one configuration or during certain portions of a medical procedure and generally rigid or stiff in another configuration or during other portions of a medical procedure. It may be desirable to have a medical instrument such as a needle that is generally flexible when located within a catheter and generally rigid when located outside of the catheter. It may be attractive to provide a variable stiffness medical device that can be mass-produced relatively inexpensively, that has a minimal number of parts, and that is easy to operate.